Immigration Minister James Brokenshire said claims she was denied medical assistance would be investigated.

Allegations that staff at the centre, which is run by Government contractor Serco, then refused the local NHS's offers to help other inmates who were distressed after the death will be also be analysed, he said.

Mr Brokenshire was speaking i n response to an urgent question by shadow home secretary Yvette Cooper in the Commons.

John Tolland, director of Yarl's Wood, said that Ms Case had been at the centre for 10 days.

She was given a "full medical assessment" by a doctor when she arrived, he said in a statement.

He explained that she became ill "soon after getting up" on Sunday.

" Her room mate activated the alarm and an officer came immediately, assessed the situation and summoned our emergency response nurse by radio," he said.

"We have 24-hour, seven-day urgent medical cover on site at Yarl's Wood. The nurse was at Ms Case's side within three minutes and started treating her, while telling the control centre to call for an ambulance and asking for further backup from the centre's own medical staff.

"Because this incident happened during the changeover between the night and day shifts, there were actually more nurses available than at any other time during the day, and a number of these went to Ms Case's assistance.

"The NHS East of England Ambulance Service responded immediately, and despatched a rapid response car, an ambulance and a Magpas air ambulance.

"Sadly, despite the efforts of the attending doctor, paramedics and the centre's medical staff, Ms Case did not regain consciousness and was pronounced dead at the scene."

He added: "I n the aftermath of this terrible event we have spared no effort in supporting the other residents in coming to terms with the death of a popular and respected member of our community here.

"Our clergy have played an outstanding role in this. On Sunday morning, for example, our pastor spoke to the congregation at our weekly Christian service about Ms Case's passing. We also brought in additional care and welfare staff on Sunday and they remain on hand to help."

He said Ms Case's death would be investiga ted by the Prisons and Probation Ombudsman.

An inquest will be opened tomorrow at Ampthill Coroner's Court, Bedfordshire.